Method and apparatus for coating of filaments

ABSTRACT

A plurality of glass filaments are drawn downwardly from a supply of molten glass, such as a glass melting bushing, into tangential contact with a transversely elongate lip of a molten metal to yield a coating of the metal on one side of the filament, followed by further downward movement momentarily contactingly past a contact surface, preferably as provided by a rod or bar or the like formed of a material resistant to the temperature of the molten metal; the filaments being slightly bent as they pass the contact surface; said contact creating an urgement of said molten metal into full envelopment of individual filaments.

[ METHOD AND APPARATUS FOR COATING OF FILAMENTS [76] Inventor: Bordie B. Garick, 1564 Kenarbre Drive, Newark, Ohio 43055 [221 Filed: Jan. 18, 1971 [21] Appl. No.: 107,195

Related US. Application Data [63] Continuation-impart of Ser. No. 777,001, Nov. 19,

1968, abandoned.

[52] [1.8. CI. .Q 118/420 [51] Int. Cl. B056 3/176 [58] Field of Search 118/420, DIG. 19,

3,231,459 [/1966 Warthen 117/126 CM X 3,507,250 4/1970 Dew, Jr 118/420 X 3,227,577 1/1966 Baessler et a1.... 118/420 X 3,371,995 3/1968 Pultz 117/106 R X Primary Examiner-Morris Kaplan Attorney-Staelin & Overman [5 7 ABSTRACT A plurality of glass filaments are drawn downwardly from a supply of molten glass, such as a glass melting bushing, into tangential contact with a transversely elongate lip of a molten metal to yield a coating of the metal on one side of the filament, followed by further downward movement momentarily contactingly past a contact surface, preferably as provided by a rod or bar or the like formed of a material resistant to the temperature of the molten metal; the filaments being slightly bent as they pass the contact surface; said contact creating an urgement of said molten metal into full envelopment of individual filaments.

4 Claims, 3 Drawing Figures PATENIEDJIILB? ms SHEEI 1 BF 2 FIG.

A-n-mzneqs v PATENTEU Jlll31 I975.

INVENTOR. Somme EZGARXCK BY .1 g METHOD AND APPARATUS FOR COATING or FILAMENTS materials onto continuously drawn-glass filaments presents a number of problems, particularly when it is appreciated that the glass filaments can be and are drawn at extremely high rates of speed, inthe neighborhood of l 5,000 feet per minute or more. Themovement of a filament at this speed results inafilm ofsurrounding air being carriedzwiththefilament. Thistends to result in a chilling effectwhich can adversely affect the successful application, to the surface of the glass, of the molten-metal-since it tends'to revert to the solid state upon contact with the cooler air carried by the-filaments.

Fairly complicated die. arrangements have been employed' to provide coatings-on filaments. However, in the production-of glass strands, the individual filaments drawn at such high speeds are usually in groups of 204 to 408 or. more filaments. As a consequence, the employment of individualdies isextremely cumbersome since each individual filament would have to vbe threaded through the dieaperture and, furthermore, in the event of a breakdown, a. considerably downtime would be involved in. stopping the operationfor rethreading of anyone or more. of the filaments not being satisfactorilycoated.

Metal-coated glass. filaments. are extremely useful materials. The. metal-coated fibers are much more abrasion resistant than the bare fibers. It is believedthat the improved: abrasion resistance. in metallizedglass'fibers" occurs. by reason of the higher thermoconductivity ofmetalcomparedlto glass,.permitting-removal of heat at a more rapid ratefront zones of point contact along. the length of abrading fibers. Metalcoated fibers have greater. applicationin use byreason ofv such higher abrasion resistance, but in additioncan be utilized advantageously in the molding of resins wherein the metal on the fibers can be inductively heated for curing or settingof. the resin inwhichthe fibers are incorporatedduring molding. Condenserscan also be made of metallizedicontinuous fibers such as by winding alternate layers of aws'tack of. glass fibers with metallized glass fibers- Metallized glass fibers can also be used to reinforce hoses such as petroleum hoses, or can be used to'provide anchoring zones inplastic or resin products wherein a: concentrated mass of metallized fibers. act. a'sspiders in. fastening zones which permit threading or more solidanchoringof bolts, screws,

or other fastening. devices to the product. Aluminum-' coated glass filaments arealso very useful by reasonof the sensitivity of electronic'sig'nals'totheir reflectivesurface. Large quantities of the aluminum-clad filaments droppedfromaircraft serve to screen or confuse radar trackingof the aircraft.

Attempts to produce aluminum-coated glass filaments in commercial quantities have demonstrated the difficulty in obtaining complete surface coverage of all filaments. Less than fulllsurface coverage, of course,

the'particular application. of use'i Accordingly, it is a adversely affects the performance of the filaments in method and apparatus which permit the manufacture of aluminum-coated glass filaments exhibiting essentially percent surface coverage by the aluminum.

It is additionally'anobject of the present invention to provide method and apparatus as will attain the foregoing while at the sametime allowing high speed production in terms of the pulling rate of the filaments from thefilament-producing bushing.

It is additionally an object of the present invention to provide method and apparatus which in retrospect 05 of relatively simplified construction as compared to priorart apparatus and techniques known to the present time.

It is still another object of the present invention to provide the aluminum-clad filaments which evidence extreme surface smoothness and uniformity of coating thickness.

The foregoing, as well as other objects of the present invention, will become apparent to those skilled in the artfrom the following detailed description taken in conjunction with the annexed sheets of drawings on which there is presented, for purposes of illustration only, a single embodiment of the present invention.

IN THE DRAWINGS FIG. 1' is a three-quarter perspective view illustrating the employment of the'apparatus and the process of the present invention; portionsof the apparatus concerned being broken away in the interest of clarity,

FIG. 2 is likewise a perspective view, similar to FIG. I, but showing one'segmentof the apparatus of the present invention greatly enlarged for purposes of illustrating details of construction and also the sequential movement of the filaments :therethrough; and

FIG. 3 is a view similar t0 FIG. 1 but showing only one segment of the moving filaments.

The inventive process and apparatus concerned will be described herein in connection with the coating of glass filaments by aluminum. It shall be appreciated,

however, that the particular techniques, the method and the apparatus disclosed will have utility in a broader sense; namely, in the coating of elongate filament or'strand-like material witha coating of a material which is heat-softenable; By. heat-softenable is meant that the material is capable of existing in the liquid state for purposes of application while liquid and also in the solid state when subjected to a lower temperature usually associated with ambient conditions.

7 In keeping with the above, it will be appreciated that the filament element need not or is not necessarily limited to glass but can be any one of a number of wiretype materials such as of aluminum, copper or steel or,

'tadiene styrene copolymers, polycarbonates, polyamides, etc. In a broader sense, thermosetting materials as liquid polymerizates could be applied as liquids to a catalyst bearing filament followed by a heating to convert the coating to the thermoset condition.

Referring now more particularly to the drawings, there is shown in FIG. 1 a general layout of the apparatus for producing fibers or filaments of glass coated, in the present instance, with aluminum. Reference numeral l identifies a melter suitable for melting glass. A feeder or bushing 11 is located within the melter and is provided with a series of outlets in its bottom from which flow a plurality of streams of molten glaSs. The outlets are in the form of projections or tips 12 at the bottom of the feeder and are preferably arranged in several rows so that the streams are substantially in the same plane.

The bushing 11 is made up of high-temperatureresistant conductive material such as platinum surrounded by refractory material retained in a steel casing, as shown. The streams flowing from the outlets, particularly the tips 12, are drawn into fiber form or filaments 14 by means of rotating, collet-supported, collecting tube 21 which winds the fibers thereon in strand form and also provides the pulling force necessary to attenuate the streams into the fine diameter of fiber or filament desired. A gathering member 19 serves to collect the plurality of filaments into a strand 23 and is loeated in a position intermediate the feeder 11 and the collecting tube 21. The type of gathering member shown in FIG. 1 is commonly termed a pad holder in that in practice it usually supports a felt-like pad of material which acts as a wick to retain sizing or lubricating fluids fed thereto from a source connected to a supply tube 13 having its outlet disposed above the gathering member 19. A brass-gathering spool of the type insulated in FIG. 3 and having a peripheral groove is frequently preferred as a gathering member for collecting the individual filaments into a unitary strand.

Sizing materials may, of course, be applied separately from the gathering member. Typical sizing materials are described in U.S. Pat. No. 2,234,986. Other lubricants may be more beneficial for strictly metal coatings. Such materials include those of perhaps more lubricating properties such as petroleum oil, vegetable oil, molybdenum disulfide, etc.

The disposition of the strand on the tube 21 to form a package is effected by a suitable traversing means such as a spiral wire traverse 22 arranged upon rotation to sweep the strand material back and forth along the axis of the collection tube with each revolution of the traverse 22.

The apparatus for imparting or applying to the filaments the coating of aluminum is identified by the reference numeral 40 and, as shown, is disposed beneath the feeder 11 and intermediate the feeder and the gathering member 19. The coating apparatus 40 is composed generally of a container-like body 42; in this case, formed of a ceramic or refractory material such as graphite having properties, such as temperature resistanee, sufficient to withstand the temperature of the molten aluminum contained therein. Situated within the refractory are a plurality of electrical conductors 44 made of, for example, Nichrome which provide the heat necessary to melt and maintain the molten material within the container at the desired temperature. Other principles of heating may, of course, be employed. The container 42 includes a well or reservoir segment 46 in which is contained the molten aluminum A. One wall 47 of the container is somewhat shorter than the other and includes an upper edge surface 49 having formed thereon an upstanding inverted shaped projection 51 which extends along the upper surface of the wall in spaced parallelism with the outer corner edge 52. Outer surface 48 of wall 47 extends reversely inwardly in order to accommodate irregularly shaped refractory member 53 which includes a notch 55 having situated therein a rod member and held by any suitable arrangement. The'r od extends in spaced parallelism beneath the edge 52 of the wall 47 and situated generally therebeneath and perhaps slightly inwardly with respect thereto as provided by the inclined surface 48.

The disposition of the applicator structureis such that the multiplicity of filaments drawn from the plurality of outlets l2 proceeds essentially vertically downwardly proximate the corner edge 52 and thence down into contact with the rod 60 and thence slightly inwardly at an angle to the alignment of the filaments proceeding downwardly from the bushing or feeder outlets 12.

This cooperates with the arrangement of the aluminum within the reservoir. The molten aluminum is maintained at a level as will provide, by gravity, a gradual flow of aluminum over the uppermost terminus of the projection 51 toward the edge 52. Furthermore, the arrangement as described, having in mind the viscosity of the molten aluminum at the temperature desired, generally in the range of I300F. or higher, together with the inherent surface tension of the aluminum, will result in the aluminum proceeding to the edge 52 and extending slightly therebeyond, forming, as it were, a lip, an overhang or meniscus identified by the reference numeral 56. This overhanging lip extends all along the edge 52 of wall 47 and is thereby available for contact by the downwardly proceeding plurality of continuous glass filaments. The contact of the filaments with the overhanging lip in its passage downwardly causes an amount of the aluminum to be picked up along the facing side of the filaments which adheres to the surface of the glass filament which is by nature hydrophylic and receptive to the coating of the molten aluminum along that side. Complete immersion of the filament in the overhanging lip is generally impractical considering the large number of filaments and the difficulty in trying to hold them to a precise location or dimension as would find all of them immersed in the projecting lip which only measures about three-sixteenths inch. Further, the high speed compounds the difficulty as does the vertical distance. it is therefore more practical to have the filament engage the outer surface of the lip of molten metal. Placement of the applicator such that the filaments definitely contact the lip will find the surface tension resulting in a sort of floating of the filaments on the surface as they pass by.

In accordance with the invention, the partial coverage on the facing surface of the filament is effected as described hcreinabove. The what may be termed hall'- coated filament then proceeds downwardly into contact with the rod member 60 and hence therebelow at a slightly different angle, as illustrated in the drawings. The movement of the half-coated filament against the rod results in the formation of a slight bulge or ball of the aluminum just above the rod or as the filament approaches the rod; said bulge being identified by the reference numeral 65. Almost simultaneously, the slight excess of material represented by the bulge, which is constantly replenished by the descending supply of aluminum borne on the filament, is urged into complete envelopment of the filament or fiber in the manner illustrated and in the region identified generally by the reference numeral 67. It will be appreciated that the now fully-coated filaments are gathered together with or without an appropriate size or lubricating material and wound onto a package as illustrated in FIG. 1. The

package may then be further. processed by packaging, 5

cutting, combining, etc., as may be desired or required bythe particular application to which the metallized filament is to be put.

in the drawings, the path of the individual filaments has been illustrated as being almost exactly vertical. It

should be appreciated that the path of the filaments can be at an angle in moving from the lip of molten aluminum to the winder.

The amount of aluminum or other metal applied to the surface of the filaments may to an extent be varied by appropriate correlation of adjustment as to the speed of the filament and the viscosity of the alloy and the choice of the alloy. By way of example, using an aluminum alloy of the composition set forth in Table 1 below and identified in the aluminum industry as A l l 00:

Table 1 Aluminum 99% Unspecified (Iron &

Silicon) l rnax mum Total 100% and a linear speed of filament draw of 2800 ft./min., an aluminum thickness ofabout 0.000125 inch is obtained as determined by an average of a series of measurement of the diameter of a coated filament. The coated filament measured an average of 0.0010 inch in diameter,

whereas the uncoated filament measures 0.00075 inch 3 in diameter.

It will be appreciated that the triangle configurated projection serving as a dam allowing flow and formation of the overhanging lamp represents the most basic and therefore most preferred type of configuration for providing the condition making possible the overhang or lip.

Thus, the projection could in theory be in the form of about any geometric shape or contour. Furthermore, instead of an upstanding projection, a groove, ditch or depression in the surface will serve to cooperate with the surface tension in the allowing of flow and the formation of the overhang or lip at the edge of the margin.

Additionally, in the case of a groove or depression in place of the inverted V-shaped darn, it is frequently desirable to have one or more conduits formed in the wall extending communicatingly from the groove or depression to the container reservoir proper. Such a structure will, it can be seen, connect the portion of molten aluminum in the overhang or lip with the molten aluminum in the reservoir and particularly the segment of the aluminum in the reservoir which is below the normal surface. Other arrangements can also be employed to assist in the formation of the overhanging lip which assists in the accomplishments of the several objects of 6 projection 51.

By way of example, glass fibers can be coated with a variety of compositions of metal. Illustrative of several suitable alloys of aluminum are the following: (1) an alloy of 5% calcium, 95% aluminum; (2) an alloy of 5l0% zinc, 90-95% aluminum; (3) an alloy of 22% copper, 78% aluminum; (4) an alloy of 5% magnesium, 5% zinc, 90% aluminum; (5) an alloy of 20% magnesium, 10% zinc, 70% aluminum; and (6) an alloy of magnesium, 70% aluminum. Alloys of lead which are illustrative of alternative metallic coatings are an alloy of l-30% zinc, l .5% cadmium, 68 5-97.5% lead. Other alloys may include, as co-alloying elements, silver, tin, copper, tellurium and antimony.

The rod element is desirably formed of a material which is resistant to the erosive and corrosive effects of the molten metal being applied as further aggravated 5 by the high speed at which the coating is being applied to the rapidly moving glass filaments. Various refractory materials may be employed. The high-temperature-resistant silicates, particularly the magnesium silicates, are particularly efficacious and long lived in such application. The magnesium silicate, mullite, having the formulation 3Al 0 -2SiO is particularly desirable due to its extremely high melting point of in the neighborhood of just over l800C.

It will be appreciated that the employment of the circular rod represents a preferred embodiment of the present invention in providing a contact surface. It has also been found that the rod preferably measures from about one-sixteenth to one-eighth inch in diameter so that the contact of the fibers therewith is quite brief. The contact surface could, of course, be provided by a variety of members either as separate elements of a given configuration or as an integral surface formed in the applicator wall in the region beneath the lip of mol ten material and transverse to the path of downwardly moving filaments. As indicated, the surface should be such as to involve a very small increment of line contact and should be fabricated of a material refractory to the molten material.

Modifications may be resorted to in the practice of the present invention and all obvious equivalents of specific details of construction and operation are intended to be included within the scope of the claims unless clearly violative thereof.

I claim:

l. in a combination reservoir and feeder apparatus for applying molten metal to a plurality of glass filaments, controlled to move downwardly in generally sp aced parallel array, comprising:

a heatable container reservoir for a supply of said molten metal, said container including marginal walls, one of said walls including an upwardly facing surface having an outer edge and an upstanding dam formed thereon in generally spaced parallel relationship with said edge, said dam and edge cooperating to control flow of molten metal thereover and formation of an overhang of molten metal available for pickup contact by said downwardly loping relationship with said filaments. 2. Apparatus as claimed in claim 1, wherein said rodlike member is a silicate.

3. Apparatus as claimed in claim 2, wherein said rodlike member is an aluminum silicate.

4. Apparatus as claimed in claim 3, wherein said aluminum silicate has the general formula 3Al -2SiO 

2. Apparatus as claimed in claim 1, wherein said rod-like member is a silicate.
 3. Apparatus as claimed in claim 2, wherein said rod-like member is an aluminum silicate.
 4. Apparatus as claimed in claim 3, wherein said aluminum silicate has the general formula 3Al2.2SiO2. 